There is an increased awareness of the possibility of attacks on metropolitan areas using chemical, biological and radiological warfare agents. Researchers at the Oak Ridge National Laboratory (ORNL) have developed a biosensor system to detect toxic agents in primary-source drinking water, such as disclosed in U.S. Pat. No. 6,569,384 to Greenbaum et al. through the analysis of fluorescence induction curves. U.S. Pat. No. 6,569,384 to Greenbaum et al. discloses a water quality sensor for detecting the presence of at least one chemical or biological warfare agent. The sensor includes a cell, apparatus for introducing water into the cell and discharging water from the cell adapted for analyzing photosynthetic activity of naturally-occurring, free-living, indigenous photosynthetic organisms in water; a fluorometer for measuring photosynthetic activity of naturally-occurring, free-living, indigenous photosynthetic organisms drawn into the cell. An electronics package analyzes raw data from the fluorometer and emits a signal indicating the presence of at least one chemical or biological warfare agent in the water. Although the water quality sensor disclosed in U.S. Pat. No. 6,569,384 to Greenbaum et al. provides highly useful devices, it would be desirable to improve the speed and sensitivity of the device.